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a+b+c=198 b-c=123 2a+b+3c= ?


Răspuns :

a+b+c = 198 |×2
2a+2b+2c = 396
b - c = 122
2a+2b+2c - (b - c) = 396 - 122
2a+2b+2c - b + c = 274
2a+b+3c = 274